Circuit Description
The 4th clutch pressure switch is located in the hydraulic passage to the 4th clutch. When oil pressure is supplied to the 4th clutch, the switch is grounded, LOW. When oil pressure is not supplied, the switch is open, HI. The PCM receives the signal from the 4th clutch pressure switch to detect the fluid pressure status, in order to reduce the shift shock when shifting into 4th gear, from 3rd to 4th or 5th to 4th.
If the 4th clutch pressure switch is OFF when the gear ratio is 4th gear, the PCM determines it is a fault and DTC P0873 sets. DTC P0873 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0873 Transmission Fluid Pressure (TFP) Switch 3 Circuit High Voltage
Conditions for Running the DTC
| • | No ECT DTCs P0116, P0117, P0118. |
| • | No VSS DTCs P0501, P0502, or P0503. |
| • | No TR Switch DTCs P0705 or P0706. |
| • | No AT ISS DTCs P0716, P0717, or P0718. |
| • | No Clutch PC Solenoid 1 DTCs P0746 or P0747. |
| • | No Shift Solenoid Valve Performance DTCs P0751, P0752, P0756, P0757, P0761, or P0762. |
| • | No Clutch PC Solenoid 2 DTCs P0776 or P0777. |
| • | No Incorrect Shift Pattern DTC P0780. |
| • | No Clutch PC Solenoid Electrical DTCs P0962 or P0963. |
| • | No Clutch PC Solenoid 2 DTCs P0966 or P0967. |
| • | No SS 1 DTCs P0973 or P0974. |
| • | No SS 2 DTCs P0976 or P0977. |
| • | No SS 3 DTCs P0979 or P0980. |
| • | No TAC DTCs P2101, P2108, P2111, or P2112. |
| • | No Minimum Idle Position DTC P2176. |
| • | No TCC PC Solenoid DTCs P2763 or P2764. |
| • | No TCC Enable Solenoid DTCs P2769 or P2770. |
| • | System voltage is greater than 10 volts. |
| • | The transmission is in D range 4th gear for 2 seconds or greater. |
Conditions for Setting the DTC
The 4th clutch pressure switch is OFF when the transmission is in 4th gear, for 2 seconds or greater.
Action Taken When the DTC Sets
| • | The PCM illuminates the service vehicle soon (SVS) lamp. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records. |
| • | The PCM stores DTC P0873 in PCM history. |
Conditions for Clearing the SVS lamp/DTC
| • | The PCM turns OFF the SVS lamp when the condition no longer exists. |
| • | A scan tool can clear the DTC. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the connectors at the PCM, the transmission fluid pressure switch, and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Wiring Systems. |
| • | Inspect the 4th clutch pressure switch for a disengaged connector. |
| • | Inspect the 4th clutch pressure switch for open wires. |
| • | Inspect the 4th clutch pressure switch for a stuck OFF condition. |
| • | Inspect for an internal fault of the PCM. |
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM. Does DTC P0873 run and fail? | Go to Step 3 | Go to Diagnostic Aids | ||||
3 |
Does the scan tool display LOW? | Go to Step 6 | Go to Step 4 | ||||
4 | Test the 4th clutch pressure switch signal circuit for an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 5 | ||||
5 | Inspect for poor connections at the PCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 | ||||
6 | Inspect for poor connections at the 4th clutch pressure switch harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 | ||||
7 |
Important: Always perform the PCM set up procedure.
Did you complete the replacement? | Go to Step 9 | -- | ||||
8 | Replace the 4th clutch pressure switch. Refer to 4th Clutch Pressure Switch Replacement . Did you complete the replacement? | Go to Step 9 | -- | ||||
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 10 | Go to Step 2 | ||||
10 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
